Genetic Basis of Sterility in Hybrids between An. gambiae and An. quadriannulatus

Matings between closely related species often produce partially or completely sterile offspring. In the Anopheles gambiae complex male sterility is present in F1 hybrids between species. F1 females are fertile, but backcross females exhibit varying degrees of sterility. We are taking two different approaches to examing this issue; a QTL mapping approach and RNAseq analyses of hybrid spermatogenesis.

In previous work we examined the genetic basis of sterility in male and female backcrosses between An. gambiae and An. arabiensis (Slotman et al. 2004, 2005) by creating QTL maps which, in the maps presented, indicate the location of male and female sterility factors in An. gambiae that cause sterility in an An. arabiensis genetic background. We are currently extending this study to backcrosses between An. gambiae and another sibling species, An. quadrianulatus. The main question is whether the gambiae genetic factors that cause sterility in an An. arabiensis background, also cause sterility in an An.quadriannulatus background.

Our second approach consists of a RNAseq analyses of hybrid spermatogenesis. We are using next generation sequencing to examine how hybridization between An. gambiae and its sibling species, An. quadriannulatus affects gene expression. We do this by comparing gene expression profiles of males from both species, as well as of the F1 male hybrids. The main question driving this work is to what extend Dobzhansky-Muller incompatibilities affect gene expression, e.g. through trans-regulatory factors, and to what extend hybrid sterility is caused by a under- or over expression of genes involved in spermatogenesis or oogenesis.